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SKELETAL SYSTEM

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FUNCTIONS SUPPORT & SHAPE - organs and tissues of the body

are held in place by the skeleton.

PROTECTION provides a rigid surface for protectionof vital organs ie. cranium protects the brain

MOVEMENT bones provide a base for muscleattachment. It allows movement of the body throughusing the bones as levers.

PRODUCTION & bones provide a site formanufacture of red & white blood cells STORAGE - storage of minerals. Ie.calcium

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Why do you need your bones?

Your bones protect

your other importantbody parts.

Your bones give youshape.

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My skull

protects

my

brain.

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My rib cage

protectsmy

heart

andlungs.

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What would you look like

without bones?Without bones

inside you

to give you shape,you would be a

BLOB!

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Skeletons have 5 major functions

Support & Shape

Movement

Protection of internal organs

Produce blood cells

Store materials

SKELETAL SUPPORT

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There are three main types of skeletons

Hydrostatic skeleton

Exoskeleton

Endoskeleton

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Hydrostatic skeleton

Consists of fluid held under pressure in aclosed body compartment

Protects body parts by cushioning themfrom shock

Provides body shape, which can bechanged by contracting muscles in the

body wall Provides support for muscle action

Earthworms, hydras, and jellies havehydrostatic skeletons

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The hydrostatic skeleton of a hydra

Figure 30.2A

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An earthworm

Figure 30.1D

1

Longitudinalmusclerelaxed

(extended)

2

Circularmusclecontracted

3

Bristles

Circularmusclerelaxed

Longitudinalmusclecontracted

Head

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Exoskeleton

Rigid external skeleton

It can be hard or leathery

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The shells ofmollusks are

exoskeletons madeof calcium carbonate

The exoskeleton ofarthropods is madeof chitin

Figure 30.2B, C

Shell (exoskeleton)

Mantle

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Endoskeleton

Consists of hard orleathery supporting

elements situated amongthe soft tissues

Most echinoderms,including sea stars and

sea urchins, have anendoskeleton of hardplates beneath their skin

Figure 30.2D

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Vertebrate endoskeletons consist of cartilage

or a combination of cartilage and bone

Figure 30.2E

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Human Skeleton

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STRUCTURE OF SKELETON There are about 206 bones found in an adult skeleton.

The bones are divided into two main groups

(1) AXIAL SKELETON

(2) APPENDICULAR SKELETON

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AXIAL SKELETON

The axial skeleton formsthe basic structure

supporting the rest ofthe skeleton.

It consists of: Skull

Vertebral column

Rib cage

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APPENDICULAR SKELETON

Forms mainly theextremities of thebody and their

connections to theaxial skeleton

Consists of

- limbs (arms &

legs)

- shoulder and pelvic

girdles

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What can you do to take care

of your skeletal system?

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The end!